如何清除实体框架中的跟踪实体 [英] How do I clear tracked entities in entity framework

问题描述

我正在运行一些在一大堆实体上运行的更正代码，随着它的进展其速度降低，这是因为上下文中跟踪的实体数量随着每次迭代而增加，这可能需要很长时间，所以我正在保存更改在每次迭代结束时.每次迭代都是独立的，不会改变先前加载的实体.

I am running some correction code that runs over a big pile of entities, as it progress its speed decreases, that is because the number of tracked entities in the context increase with each iteration, It can take long so I am saving changes at the end of each iteration. Each iteration is independent and does not change the previosuly loaded entities.

我知道我可以关闭更改跟踪，但我不想，因为它不是批量插入代码，而是加载实体并计算一些事情，如果数字不正确，请设置新数字并更新/删除/创建一些额外的实体.我知道我可以为每次迭代创建一个新的 DbContext 并且可能比在同一实例中执行所有操作运行得更快，但我认为可能有更好的方法.

I know I can turn off change tracking but I do not want to, because it is not a bulk insert code, but loading the entities and calculating a few things and if the numbers are not correct set the new numbers and update/delete/create some additional entities. I know I can create a new DbContext for each iteration and probably that would run faster than doing all in the same instance, but I am thinking that there might be a better way.

所以问题是；有没有办法清除之前在db上下文中加载的实体?

推荐答案

您可以向 DbContext 添加方法或使用 ChangeTracker 分离所有已添加、已修改和已删除的扩展方法实体:

You can add a method to your DbContext or an extension method that uses the ChangeTracker to detach all the Added, Modified, and Deleted entities:

public void DetachAllEntities()
{
    var changedEntriesCopy = this.ChangeTracker.Entries()
        .Where(e => e.State == EntityState.Added ||
                    e.State == EntityState.Modified ||
                    e.State == EntityState.Deleted)
        .ToList();

    foreach (var entry in changedEntriesCopy)
        entry.State = EntityState.Detached;
}

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